#include <bits/stdc++.h>
#define rep(i, l, r) for(int i = l; i < r; i++)
#define hrp(i, l, r) for(int i = l; i <= r; i++)
#define rev(i, r, l) for(int i = r; i >= l; i--)
#define int ll
using namespace std;
typedef long long ll;
template<typename tn = int> tn next(void) { tn k; cin>>k; return k; }
#ifndef LOCAL
#define D(...) 0
#define I(...) 0
#endif
const int U = 7e5;
int cen[U], mxs[U], siz[U], fa[U];
vector<int> edge[U];
bool chkmin(int&a, int b) { return a > b ? a = b, 1 : 0; }
void dfs(int e, int f)
{
    siz[e] = 1; cen[e] = e; fa[e] = f;

    for(auto y: edge[e]) if (y != f) dfs(y, e), mxs[e] = max(mxs[e], siz[y]), siz[e] += siz[y];

    for(auto y: edge[e]) if (y != f)
    {
        int now = cen[y];
        while(now != e)
        {
            if (max(mxs[now], siz[e]-siz[now]) <= siz[e]/2) { cen[e] = now; break; }
            else now = fa[now];
        }
    }
}
signed main(void)
{
    #ifdef LOCAL
//	freopen("C:\\Users\\Loxil\\Desktop\\IN.txt", "r", stdin);
//	freopen("C:\\Users\\Loxil\\Desktop\\OUT.txt", "w", stdout);
    #endif
    
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int n;
    cin>>n;
    rep(i, 1, n) { int f, t; cin>>f>>t; edge[f].push_back(t); edge[t].push_back(f); }

    dfs(1, 0);

    hrp(i, 1, n)
    {
        cout<<cen[i];
        if (fa[cen[i]] && max(mxs[fa[cen[i]]], siz[i]-siz[fa[cen[i]]]) <= siz[i]/2) cout<<' '<<cen[fa[i]];
        cout<<endl;
    }
    
    return 0;
}
/*

 */